how to connect a bluetooth device (headphone or speaker box) in a2dp bluetooth profile, and in sink role, to an eval adau 1467Z board ?
Hello
I would like to send one or many stereo outputs of my eval adu 1467Z board to some cheap off the shelf hardware which will convert it to wireless (bluetooth) so that it can be received by any mainstream BT wireless speakers or headphones.
Have anyone tried and suceeded in doing so ?
I have seen cheap devices doing the other way round (ie BT receiver as input & outputing i2s and/or analog).
I put this constraint : the signal shall stay in digital form all the way until it arrives at the DAC inside the BT speaker/headphones, ie i want ot use the I2S outputs present on the eval board (spdif out would be ok but, alas there is only one available), and not the analog ones.
Thanks in adavnce
Cheers
i2s outputs
bluetooth
hardware
sigma studio 4.7
a2dp
eval adau 1467z
Show More
Hello iravelo,
You can take I2S signal out from our serial output port. Three serial output port headers are available in this Eval board. Devices like ESP32 has both I2S and Bluetooth interfaces. So, you can receive the I2S signal in ESP32 and transmit it via Bluetooth Tx to any of your Bluetooth speaker or headphone which obviously has a DAC in it. Is that what you are expecting?
How many stereo outputs do you want? If you want more than three, then you need to configure the SDATAIO pins in the serial port section. You can find some of the SDATAIO pin headers in port J5. Each SDATAIO pin can carry an I2S signal. These pins are multiplexed with MP pins. You can find this in page 52 of the datasheet. I guess, maximum you will get around six stereo outputs in total. Let me know if you want more details on this.
what is your sample rate?
I hope you will get an idea. Kindly do reply if you need anything.
Regards,
Harish
hi Harish, I get the point : use the esp32 as it is programmable to do whatever we want, like read from one of its i2S interfaces, and then forward the audio flow to a distant BT device. I still need to find existing libraries to help doing standard A2DP, can you direct me to some URL ? . My main idea is to use only one or two I2S outputs from the ADAU board. Regarding the sample rate, I have no clue for now, but I suppose bluetooth protocol needs a speed it has standardized, and the ADAU will need to convert its saple rate and and bit width to this stardard. could that mean the beginning of serious trouble ?
Cheers
I've just found this https://github.com/nopnop2002/esp-idf-a2dp-source where they claim they manage to send some sound to a BT speaker. I cannot see when the codec comes into action, as I don't think the bandwidth of a2dp can accomodate with .WAV file raw data at 44.1KHz 16bits, which might not be the default config for the adau 1467 dsp.
here is another shared source code github.com/.../base-i2s-a2dp where he/she seems to forward i2s stream over BT to an a2dp sink. I did not try it yet as I do not have any i2s microphone and need to figure out what needs to be changed before replacing the i2s microphone w/ one of the ADAU's i2s output
Helllo iravelo,
I don't think it will be a problem since we have ASRCs. The ASRC will convert any incoming rate (from Bluetooth) to our core rate for proper synchronization.
Regards,
Harish
Please log in to reply.